TETANUS IN THE HORSE AND MAN 



271 



FIG. 138 



and provision must be made to exclude the oxygen of the air. In 

 soil, manure, and wounds, however, it can grow even without the 

 careful exclusion of oxygen when it is associated with aerobic micro- 

 organisms, with which it may enter into a symbiotic union. The aerobic 

 bacteria consume the oxygen, and in this way enable the tetanus 

 bacillus to multiply. On this 

 account the most dangerous 

 wounds are those which from 

 the beginning have been con- 

 taminated with both tetanus 

 and other bacteria. If such 

 wounds are thoroughly cleansed 

 with antiseptics which destroy 

 the other bacteria, but not the 

 tetanus spores, lockjaw may 

 yet not develop in spite of the 

 presence of these spores, which 

 do not readily germinate and 

 multiply when alone. It is also 

 important to note that tetanus 

 spores which have been freed 



Bacillus tetani, spore formation. (Author's 



from the tetanus toxin by wash- preparation.) 



ing with antiseptics may be 



taken up and destroyed by phagocytes. It is claimed that tetanus 

 bacilli can be successively so changed that they will grow in the 

 presence of oxygen, losing, then, their toxicity and pathogenic char- 

 acter. This statement, however, is doubted by some investigators, 

 who believe that these aerobic, non-toxic bacilli are from the beginning 

 a pseudotetanus bacterium. 



Resistance of Spores. The spores are exceedingly resistant to heat 

 and antiseptics, even more so in some respects than anthrax spores. 

 They can survive complete drying out for many years; if raised pri- 

 marily under the most favorable conditions, they can, according to 

 Smith's experiments, withstand exposure to steam of 100 C. for one 

 hour, and it is not until after an exposure of seventy minutes that all 

 tetanus spores are safely killed. 



The Bacillus as a Saprophyte. The tetanus bacillus exists extensively 

 in the outside world, particularly in garden earth and where there 

 has been much manuring; in warm countries, however, it is present 

 independent of any manuring. Some investigators believe that the 

 tetanus bacillus exists in the ground only where the latter has come in 

 contact with the feces of horses and other herbivorous animals which 

 harbor the organism in their intestinal tract; it is, however, more 

 generally held that it occurs in the soil independent of admixture 

 with fecal matter. 



Tetanus in the Horse and Man. In horses tetanus is very common 

 after nail wounds of the hoofs and after castration; in man after 



